Histopathology 15: Bone Pathology

Question 1

What part of long bones encompasses the growth plates ?

Answer 1

Metaphysis

Question 2

What are some of the main differences between cancellous and cortical bone ?

Answer 2

Cancellous bone is mainly metabolic whereas cortical is for support and protection

Cancellous bone is found as part of the axial skeleton (pelvis, vertebrae) cortical is found in long bones

Cortical bone is more calcified

Question 3

How do osteoblasts inhibit osteoclast formation ?

Answer 3

Osteoblasts release osteoprotegrin which inhibits RANKL from binding to the RANKL receptor on osteoclast precursors. This blocks differentiation into mature osteoclasts.

Question 4

List fractures commonly seen in patients with osteoporosis ?

Answer 4

Colle’s fracture of the wrist
NOF and intertrochanteric fractures of the hip
Pelvic
Vertebra

Question 5

What are the biochemistry findings in a patient with osteoporosis ?

Answer 5

Normal calcium
Normal phosphate
Normal ALP

Question 6

What are the histological findings in osteoporosis ?

Answer 6

Loss of cancellous bone

Question 7

List 2 ty typical X-ray findings suggestive of Osteomalacia ?

Answer 7

Bowing of the legs in Rickets

Horizontal pseudofractures in looser’s zones

Question 8

List signs and symptoms of Rickets in children ?

Answer 8

Bone pain
Bowing tibia
Rachitic rosary  
frontal bossing 
Pigeon chest 
Delayed walking

Question 9

What is a histological feature of Osteomalacia ?

Answer 9

Excess unmineralised bone

Question 10

List symptoms of hyperparathyroidism?

Answer 10

Moans - depression, confusion
Stones- calcium oxalate renal calculi
Bones- bone pain
Groans- constipation, pancreatitis, polyuria

Question 11

Which metabolic bone disease shows histological bone changes of osteitis fibrosa cystica ?

Answer 11

Hyperparathyroidism

Question 12

List 3 x-ray findings suggestive of hyperparathyroidism ?

Answer 12

Brown’s tumours (osteitis fibrosa cystica)
Salt and pepper skull
Subperiosteal bone resorption in phalanges

Question 13

Describe the actions of PTH ?

Answer 13

Acts directly on the bone causing increased calcium and phosphate reabsorption.

Acts on the kidneys causing increased 1 alpha hydroxylase conversion of calcidiol to calcitriol

Calcitriol (activated vit D) then causes increased absorption of dietary calcium and phosphate from the small intestine.

PTH (“phosphate thrashing hormone”) acts directly on the kidneys to cause Increased calcium reabsorption and increased phosphate excretion.

Question 14

What is renal osteodystrophy ?

Answer 14

A term that describes all skeletal changes associated with chronic renal disease

Question 15

What are the biochemistry findings in Osteomalacia/rickets ?

Answer 15

Normal/low calcium
Low phosphate
High ALP
Low Vitamin D

Question 16

What are the biochemical findings in primary Hyperparathyroidism?

Answer 16

High PTH
High Calcium
Low/normal phosphate
High/normal ALP

Question 17

What are the biochemistry findings in Paget’s disease ?

Answer 17

Normal calcium
Normal phosphate
Super high ALP

Question 18

What is the most common causative organism for osteomyelitis in adults ?

Answer 18

S.Aureus

Question 19

List 2 histological findings in Paget’s disease ?

Answer 19

Huge Osteoclasts with >100 nuclei

Mosaic pattern of lamellar bone

Question 20

List the x-ray features of osteoarthritis ?

Answer 20

L- loss of joint space
O- osteophytes
S- subchondral sclerosis
S- subchondral cysts

Question 21

List 2 features of osteoarthritis in the hands ?

Answer 21

Heberden’s nodes (DIP joints)

Bouchard’s nodes (PIP joints)

Question 22

List 6 features of rheumatoid arthritis in the hands and wrist?

Answer 22

Sparring of the DIP joints
Radial deviation of the wrist 
Ulnar deviation of the fingers
Swan neck deformity of the fingers
Boutonniere’s deformity of the fingers
“Z” shaped thumb

Question 23

List 3 histological features of rheumatoid arthritis ?

Answer 23

Proliferative synovitis
Pannus formation
Grimley sokoloff cells- multinucleate giant cells

Question 24

Which infectious organism causes osteomyelitis with Langerhans-type giant cells on histology ?

Answer 24

Tuberculosis

Question 25

Which shape Chrystal are seen in gout and pseudogout?

Answer 25

Gout = needle shaped
Pseudogout = rhomboid shaped

Question 26

Which syndrome has the following features: Blue sclera, hearing loss, miss shaped teeth and recurrent fractures ?

Answer 26

Oesteogenesis imperfecta (autosomal dominant)

Question 27

Describe the 4 stages of fracture repair ?

Answer 27

1 - Organisation of haematoma
2- fibrocartilaginous callus formation
3- Mineralisation of fibrocartilaginous callus
4- remodelling of bone along weight bearing lines